Linear, alternating polyketones formed by the copolymerization of carbon monoxide with one or more olefins (principally ethylene or ethylene in combination with a small amount of propylene) are attracting considerable recent attention as a novel and useful class of polymer. A number of flame retardant additives have been proposed for these type of polymers including the following:
U.S. Pat. No. 4,761,449 to R. G. Lutz teaches the use of an alkaline earth metal carbonate as a flame retardant for such polymers;
U.S. Pat. No. 4,885,318 to R. L. Danforth et al. advocates the use of organo halide-containing materials as polyketone flame retardants;
U.S. Pat. No. 4,885,328 to R. L. Danforth et al. teaches that an alkaline earth metal hydroxide can be utilized as a flame retardant in polyketone polymers;
U.S. Pat. No. 4,921,897 to R. L. Danforth et al. teaches the use of zinc borate or barium borate as suitable flame retardants for such polymers; and
U.S. Pat. No. 5,030,674 to V. J. Notorgiacomo advocates the use of a combination of a thermally stable cyclic phosphonate ester and a polytetrafluoroethylene resin as a polyketone flame retardant system. The phosphonate ester additive is exemplified by the ANTIBLAZE 1045 brand product which is available from Albright & Wilson Inc. The cyclic phosphonate species described in this patent all contain one or more monocyclic moieties.
Flame retardant compositions comprising certain bicyclic phosphorus flame retardant compounds and certain intumescent flame retardant compounds which are suitable for use in certain enumerated polymers, including polyolefins, polyesters, and polyamides, are disclosed in U.S. Pat. No. 4,801,625 to W. J. Parr et al. While such compositions are useful as flame retardants for such application, persons of ordinary skill in the art have additionally desired improved flame retardant compositions which have enhanced processing characteristics with the selected polymer they are intended to flame retard. Processing improvements are exhibited by one or more of the following characteristics: less porous pellets; and a smoother surface characteristic when extruded.
This improvement in the type of flame retardant system described in the aforementioned Parr patent is covered in U.S. Ser. No. 08/638,417, filed Apr. 25, 1996 which describes the use of such a system in polyolefin polymers, in particular. The bicyclic moieties shown in the various flame retardants in the aforementioned patent documents are derived from pentaerythritol phosphate alcohol.